Change in body surface temperature as an ancillary measurement to motor evoked potentials

Abstract

Study design: Experimental study. Objectives: To study the role of surface temperature as an adjunct to motor evoked potentials (MEPs) in rabbit spinal cord injury (SCI) model. Setting: Department of Orthopedics, Korea University Guro Hospital, Seoul, Korea. Methods: Rabbits (n=18) were divided into Complete (n=9) and Incomplete (n=9) SCI groups. Complete SCI was defined as being non-responsive to a wake-up test with loss of MEPs after transection of spinal cord. Incomplete SCI was defined as being responsive to a wake-up test with significant attenuation (>= 80%) of MEPs after impaction on spinal cord. Surface temperature of upper and lower extremities, core temperature and MEPs signals were checked before, during and after SCI for 20 min. A wake-up test was conducted and spinal cord was histologicaly evaluated. Results: Experimental conditions between the two groups were statistically similar (P>0.005 for all values). After SCI, upper extremity temperatures did not change in either group (P>0.005); however, the surface temperature of the lower extremities in the Complete SCI Group elevated to 1.7 +/- 0.5 degrees C in comparison to 0.5 +/- 0.1 degrees C in the Incomplete SCI Group (P<0.001). The scores of wake-up test in the Incomplete SCI Group were significantly different from that of the Complete SCI Group (P<0.001), while white and gray matter damage was variable on histology. Conclusions: Monitoring of changes of body surface temperature of the lower extremities can be potentially used to identify the completeness of SCI in a rabbit model.